The mass manufacture of products has been structured and sub-divided into individual process steps. For the manufacture of the products the unfinished products must be transported from one processing station to the next one, and so on. In some automated manufacturing processes, the unfinished products are transported from one processing station to the next one in a cyclic manner, in which consecutive processing stations are synchronized with each other.
An example for a fully automated mass manufacturing process is the mass production of ophthalmic lenses, in particular contact lenses. The manufacture of such lenses can be performed in a closed loop process. One example for a cyclic closed loop process for the manufacture of contact lenses is described, for example, in WO 98/42497. The contact lenses are manufactured with reusable molds, comprising male and female mold halves. In a first processing station the female mold halves are filled with a starting material, e.g. a prepolymer solution, and the molds are closed with the corresponding male mold halves. In the next processing station, the starting material within the molds is polymerized and/or crosslinked by irradiation with e.g. ultraviolet radiation. After the polymerization and/or crosslinking step in a next processing station the mold halves are opened and the formed contact lenses are removed from the male or female mold halves in order to transport them to further processing stations.
Depending on the starting materials from which the contact lenses are made the contact lenses must be subjected to further treatment, e.g. they must be immersed in extraction liquids and/or additional treatment liquids in order to obtain contact lenses which may be worn by the user. For a variety of reasons the cycle times of the contact lens forming process steps on one hand, and the cycle times of the extraction and/or other treatment steps on the other hand, require specific processing times in order to obtain contact lenses which are in conformance with predefined specifications. Further depending on how the contact lens forming process is realized in terms of apparatus features, it may be preferable to chose a first cycle speed for the contact lens forming steps which is different from a second cycle speed that may be preferable for the extraction and/or other treatment steps. A change of the cycle speed in any of the two processes (contact lens forming process, contact lens treatment process) in order to arrive at a uniform cycle speed of the entire process would result in very expensive changes to the apparatus concept and would necessarily result in a new qualification and validation process for the manufacturing line based on this apparatus concept.
The problems at the interface of consecutive processing stations having different cycle speeds have been illustrated by way of example with respect to the mass production of ophthalmic lenses, in particular contact lenses. It is apparent for the skilled artisan, though, that such problems may occur in various kinds of fully automated manufacturing processes, which require a transfer of objects between two consecutive processing stations having different cycle speeds. Thus, while the described problem and the solution to this problem suggested by the present invention is particularly applicable in the art of manufacture of ophthalmic lenses, in particular contact lenses, it is not limited to this field of application.
It is therefore an object of the present invention to provide a solution to the addressed problems of the prior art. A method and an apparatus for transferring objects, in particular ophthalmic lenses, more specifically contact lenses, shall be provided which allows to suggest or maintain an apparatus concept that is based on different cycle speeds but which may be otherwise preferable for the specific process steps to be performed. In particular, a new qualification and validation process for a production line based on such apparatus concept should be avoided.